NAME

       swapspace - dynamically manage swap space

SYNOPSIS

       swapspace [options]

DESCRIPTION

       Monitor  memory  and  swap  usage  and  allocate or deallocate swap space as needed.  This
       program aims to reduce or do away with the need for swapfiles.

       swapspace can be built in two configurations: the full-featured  one  (which  is  now  the
       default)  or the unconfigurable version.  The latter only accepts a few options, disabling
       all features that are probably only relevant to developers.  At some point in the feature,
       when  enough  confidence  exists that the various configuration parameters are either good
       enough for everyone or have been made unnecessary, the unconfigurable build may become the
       default.

       The  following options are accepted in the unconfigurable version.  All of these have more
       extensive equivalents in the full-featured version.

       -d     Quietly ignored; always enabled in unconfigurable version.

       -e     Attempt to free up  all  allocated  swap  files.   Returns  0  if  all  files  were
              successfully erased, or 1 otherwise.

       -h     Display usage information and exit.

       -p     Write  process  identifier  to  /var/lib/swapspace.pid when starting (and delete it
              when shutting down).  The file's  name  and  location  cannot  be  changed  in  the
              unconfigurable version.

       -q     Quietly ignored; always enabled in unconfigurable version.

       -v     Quietly ignored; always enabled in unconfigurable version.

       -V     Print program version information and exit.

       In  most  cases,  these  should  be the only options of any interest for normal use of the
       program.  All files are kept in their default locations, which were chosen  in  accordance
       with  the  Linux  Filesystem  Hierarchy  Standard,  and algorithmic parameters are left at
       defaults that have been tested to work well for a wide range of uses.

       The full-featured configuration accepts more options, as listed  below.   The  long-format
       options  may  also  be  specified,  without the leading "--", in a configuration file.  By
       default, /etc/swapspace.conf is read on startup.

       -a duration, --cooldown=duration
              If disk space runs out when allocating a swapfile, wait for duration iterations (of
              roughly  one  second  each)  before  considering  allocating one again; or if space
              doesn't run out, wait  for  duration  iterations  before  considering  deallocating
              uneeded  swapfiles.   This stabilizes the daemon's behaviour in the face of varying
              memory requirements.

       -B p, --buffer_elasticity=p
              Consider p% of system-allocated I/O buffers to be available for other use.

       -c file, --configfile=file
              Read file instead of the default configuration file.

       -C p, --cache_elasticity=p
              Consider p% of filesystem cache to be available for other use.

       -d, --daemon
              Run quietly in the background.  This is the normal way to run the program.

       -e, --erase
              Attempt to free up  all  allocated  swap  files.   Returns  0  if  all  files  were
              successfully erased, or 1 otherwise.

       -f p, --freetarget=p
              Aim to have p% of combined memory and swap space free.

       -h, --help
              Display usage information and exit.

       -l p, --lower_freelimit=p
              Try  to  keep  at  least  p% of combined memory and swap space free; if less than p
              percent is available, attempt to allocate more swap space.

       -M size, --max_swapsize=size
              Never let swapfiles become larger than size bytes.  You don't normally need to  set
              this;   the  daemon  will  learn  when  its  swap  files  get  too  big  and  adapt
              automatically.

       -m size, --min_swapsize=size
              Never bother to allocate any swapfiles smaller than size bytes.  There should be no
              need to change this variable except for testing.

       -p [file], --pidfile[=file]
              Write  process  identifier  to  file  when  starting (and delete file when shutting
              down); defaults to /var/lib/swapspace.pid.

       -P, --paranoid
              Overwrite retired swapfiles before they are deleted, so  an  attacker  who  obtains
              access  to  the disk without going through the system's access control checks (e.g.
              by unplugging the computer and then  rebooting  from  a  CD)  cannot  retrieve  the
              swapped  data.   There  is no guarantee that this will work, and it will not thwart
              advanced forensic analysis using custom-built  hardware;  but  it  may  reduce  the
              chances  of  an  attacker  with  physical access to the system obtaining passwords,
              credit card numbers etc.  The  program  will  attempt  to  free  up  all  allocated
              swapfiles  on  termination  and  return  a success code for this cleanup, as if the
              --erase had been specified.

       Caution
              The --paranoid option  will  slow  down  swap  file  management  considerably.   In
              particular,  stopping the daemon will cause it to try and deallocate (and wipe) all
              swapfiles it has created, and they will not be available for  swapping  immediately
              after reboot.

       -q, --quiet
              Suppress informational output.

       -s dir, --swappath=dir
              Create  swapfiles  in directory dir instead of default location /var/lib/swapspace.
              This location must be accessible to root only; allowing anyone  else  to  write  to
              this directory or even read swapped data would be a serious security breach.

       -u p, --upper_freelimit=p
              Avoid  having  more  than  p%  of  combined  memory  and  swap  space free; if this
              percentage is exceeded, try to deallocate swap space.

       -v, --verbose
              Log debug information to system log and/or standard output, as appropriate.

       -V, --version
              Print program version information and exit.

       Numbers may be suffixed with k, m, g or t to indicate kilobytes, megabytes,  gigabytes  or
       terabytes  respectively:  1k  means  1024  bytes,  1m  means 1024 kilobytes, 4g means 4096
       megabytes and so on.

       Timings are measured in iterations, which should typically last about one second each.  No
       pretense  of  accurate  timing is made; this is not the kind of program you would run on a
       hard-realtime system.

       Any messages are sent to the system daemon  log;  it  is  also  printed  to  the  standard
       output/error  streams  (as appropriate based on the urgency of each individual message) if
       available.

SIGNALS

       State information can be logged by sending the program the  SIGUSR1  signal  (user-defined
       signal  1).   Not  all of this information will always be current; most of the information
       internal to swapspace is only updated when needed.

       Sending the SIGUSR2 signal will make the program free all swapfiles that are not currently
       needed, and abstain from allocating any more for the timespan of one cooldown period.  The
       program will behave as if it just tried to create a swapfile but ran out of disk space.

FILES

        /etc/init.d/swapspace  /etc/swapspace.conf  /usr/sbin/swapspace  /var/lib/swapspace/

AUTHOR

       Written by Jeroen T. Vermeulen

BUGS

       Please   report   any   bugs   you   may    find    on    the    project    website    at:
       http://thaiopensource.org/development/swapspace/

COPYRIGHT

       Copyright © 2005 Software Industry Promotion Agency (SIPA), Thailand
       This  is  free  software;  see  the  source  for copying conditions.  There is no warranty
       whatsoever.  Use entirely at your own risk.

SEE ALSO

       kill(1), mkswap(8), signal(7), swapon(2), swapoff(2), swapon(8), swapoff(8)